[llvm] [llvm-objdump][AVR] Detect AVR architecture from ELF flags for disassembling (PR #174731)

[James Henderson via llvm-commits]

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@@ -2689,6 +2690,19 @@ static void disassembleObject(ObjectFile *Obj, bool InlineRelocs,
       Features.AddFeature(MAttrs[I]);
   } else if (MCPU.empty() && Obj->makeTriple().isAArch64()) {
     Features.AddFeature("+all");
+  } else if (MCPU.empty() && Obj->makeTriple().isAVR()) {
+    // Assign attributes based on the AVR architecture version, default to
+    // "avr0". Report "<unknown>" for unsupported AVR instructions to avoid
+    // silent failures.
+    if (const auto *Elf = dyn_cast<ELFObjectFileBase>(Obj)) {
+      unsigned AVRVersion = Elf->getPlatformFlags() & ELF::EF_AVR_ARCH_MASK;
+      std::string Version = AVR::getFeatureSetForEFlag(AVRVersion);
+      if (Version == "avr0")
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jh7370 wrote:

Follow-up question then: why have you chosen "avr0" as the default string?

@benshi001, could you confirm the answer to what you think we should do here, please.

https://github.com/llvm/llvm-project/pull/174731